The present invention generally relates to wire fabrics and structures. More particularly, this invention relates to tire beads and their methods of manufacturing.
A tire bead is that part of a tire which anchors the tire onto a wheel""s rim. It is essentially an annular tensile member or inextensible hoop. Every tire has two such beads which are located within the rubber which makes up the inner-most circumference on each side of the tire.
In the usual procedure for manufacturing tire beads, the ends of individual wires, the exteriors of which are often rubber coated, are fed into a tire bead making machine. Machines of this type are old and well known in the tire building art.
Typical machines of this type are disclosed in U.S. Pat. Nos. 1,913,336, 2,902,083 and 5,385,621. These machines comprise a rotating drum about which the wire is wrapped a predetermined number of turns, dependent upon the strength and/or cross-sectional area of the tire bead desired. Standard equipment on such machines includes the means for automatically introducing the leading end of the wire into a gripper on the drum, intermittently operated means for rotating the drum, a stacking device which moves the incoming wire so as to control and build-up the cross-sectional shape of the resulting tire bead, and a knife to sever the incoming wire at the end of each building cycle. During the pause in the rotation of the drum, the finished tire bead is ejected laterally from the drum.
One deficiency of conventional tire bead making machines is their relatively slow operating speeds and consequently the amount of time required to fabricate a tire bead. To overcome this deficiency, various methods have been attempted to feed such tire bead machines a strap comprised of four parallel wires held together by a coating of rubber or other elastomeric material. A rectangular cross-sectional shaped tire bead formed using a standard style strap is shown in FIG. 1.
However, because such straps are not pliable, their use has been seen to severely limit the range of cross-sectional shapes of the tire beads which can be built-up by using them. For example, a conventional hex cross-sectional shaped tire bead, see FIG. 2, which is commonly used in the tire industry, cannot be built up using the types of straps shown in FIG. 1. Also, by increasing the number of wires forming each bead, the strength of the bead is reduced.
Another deficiency of conventional tire bead making machines is the problem associated with how to deal with the cut ends of the resulting tire bead. The springback nature of the wire ends can result in their coming loose and causing wire misalignments which can result in an unacceptable number of manufacturing interruptions in order to restring and realign the wires.
Thus, despite the prior art, there still exists a need for more efficient tire bead manufacturing processes.
It is an object of the present invention to provide a more efficient tire bead manufacturing process as defined in one or more of the appended claims and as such, having the capability of accomplishing one or more of the following subsidiary objects.
An object of the present invention is to provide a method of constructing a tire bead with a strap containing two parallel wires enmeshed in an elastomeric material.
Still another object of the present invention is provide a new and improved type of tire bead formed of the strap of two parallel wires.
Other objects and advantages of this invention will become readily apparent as the invention is better understood by reference to the accompanying drawings and the detailed description that follows.
The present invention is generally directed to satisfying the needs set forth above and the problems identified with prior tire bead manufacturing processes. Prior problems, associated with low operating efficiencies for tire bead machines are resolved by the present invention.
In accordance with one preferred embodiment of the present invention, the foregoing need can be satisfied by providing a method of making a tire bead characterized by the steps of forming a tape composed of a plurality of parallel wires coated with a resilient elastomeric material, the elastomeric material connecting adjoining parallel wires by a web formed between the wires, the web being of a predetermined size so as to yield the tape sufficiently pliable so as to allow the tape to be positioned to build up a tire bead having the same cross-sectional areas that can be built using individual wires, and forming a tire bead by winding such a tape a predetermined number of superimposed convolutions.
In another preferred embodiment, the present invention is seen to take the form of the above described method wherein the winding of the tape proceeds with the convolutions of the tape being laid in side by side relation and in successive superposed layers of predetermined widths to provide a tire bead of predetermined cross-sectional area.
In another preferred embodiment, the present invention is seen to take the form of a tire bead formed by any of the above described methods.